tcpip.h File Reference

Transport-network layer interface. More...

#include <stdint.h>
#include <ipxe/socket.h>
#include <ipxe/in.h>
#include <ipxe/tables.h>
#include <bits/tcpip.h>

Go to the source code of this file.

Data Structures
struct	sockaddr_tcpip
	TCP/IP socket address. More...
struct	tcpip_protocol
	A transport-layer protocol of the TCP/IP stack (eg. More...
struct	tcpip_net_protocol
	A network-layer protocol of the TCP/IP stack (eg. More...

Macros
#define	TCPIP_POSITIVE_ZERO_CSUM   0x0000
	Positive zero checksum value. More...
#define	TCPIP_NEGATIVE_ZERO_CSUM   0xffff
	Negative zero checksum value. More...
#define	TCPIP_EMPTY_CSUM   TCPIP_POSITIVE_ZERO_CSUM
	Empty checksum value. More...
#define	TCPIP_PROTOCOLS   __table ( struct tcpip_protocol, "tcpip_protocols" )
	TCP/IP transport-layer protocol table. More...
#define	__tcpip_protocol   __table_entry ( TCPIP_PROTOCOLS, 01 )
	Declare a TCP/IP transport-layer protocol. More...
#define	TCPIP_NET_PROTOCOLS   __table ( struct tcpip_net_protocol, "tcpip_net_protocols" )
	TCP/IP network-layer protocol table. More...
#define	__tcpip_net_protocol   __table_entry ( TCPIP_NET_PROTOCOLS, 01 )
	Declare a TCP/IP network-layer protocol. More...

Enumerations
enum	tcpip_st_flags { TCPIP_BIND_PRIVILEGED = 0x0400 }
	TCP/IP address flags. More...

Functions
	FILE_LICENCE (GPL2_OR_LATER_OR_UBDL)
	FILE_SECBOOT (PERMITTED)
uint16_t	generic_tcpip_continue_chksum (uint16_t partial, const void *data, size_t len)
	Calculate continued TCP/IP checkum. More...
int	tcpip_rx (struct io_buffer *iobuf, struct net_device *netdev, uint8_t tcpip_proto, struct sockaddr_tcpip *st_src, struct sockaddr_tcpip *st_dest, uint16_t pshdr_csum, struct ip_statistics *stats)
	Process a received TCP/IP packet. More...
int	tcpip_tx (struct io_buffer *iobuf, struct tcpip_protocol *tcpip, struct sockaddr_tcpip *st_src, struct sockaddr_tcpip *st_dest, struct net_device *netdev, uint16_t *trans_csum)
	Transmit a TCP/IP packet. More...
struct tcpip_net_protocol *	tcpip_net_protocol (sa_family_t sa_family)
	Find TCP/IP network-layer protocol. More...
struct net_device *	tcpip_netdev (struct sockaddr_tcpip *st_dest)
	Determine transmitting network device. More...
size_t	tcpip_mtu (struct sockaddr_tcpip *st_dest)
	Determine maximum transmission unit. More...
uint16_t	tcpip_chksum (const void *data, size_t len)
	Calculate TCP/IP checkum. More...
int	tcpip_bind (struct sockaddr_tcpip *st_local, int(*available)(int port))
	Bind to local TCP/IP port. More...

Detailed Description

Transport-network layer interface.

Definition in file tcpip.h.

Macro Definition Documentation

TCPIP_POSITIVE_ZERO_CSUM

#define TCPIP_POSITIVE_ZERO_CSUM   0x0000

Positive zero checksum value.

Definition at line 28 of file tcpip.h.

TCPIP_NEGATIVE_ZERO_CSUM

#define TCPIP_NEGATIVE_ZERO_CSUM   0xffff

Negative zero checksum value.

Definition at line 31 of file tcpip.h.

TCPIP_EMPTY_CSUM

#define TCPIP_EMPTY_CSUM   TCPIP_POSITIVE_ZERO_CSUM

Empty checksum value.

All of our TCP/IP checksum algorithms will return only the positive representation of zero (0x0000) for a zero checksum over non-zero input data. This property arises since the end-around carry used to mimic one's complement addition using unsigned arithmetic prevents the running total from ever returning to 0x0000. The running total will therefore use only the negative representation of zero (0xffff). Since the return value is the one's complement negation of the running total (calculated by simply bit-inverting the running total), the return value will therefore use only the positive representation of zero (0x0000).

It is a very common misconception (found in many places such as RFC1624) that this is a property guaranteed by the underlying mathematics. It is not; the choice of which zero representation is used is merely an artifact of the software implementation of the checksum algorithm.

For consistency, we choose to use the positive representation of zero (0x0000) for the checksum of a zero-length block of data. This ensures that all of our TCP/IP checksum algorithms will return only the positive representation of zero (0x0000) for a zero checksum (regardless of the input data).

Definition at line 58 of file tcpip.h.

TCPIP_PROTOCOLS

#define TCPIP_PROTOCOLS   __table ( struct tcpip_protocol, "tcpip_protocols" )

TCP/IP transport-layer protocol table.

Definition at line 179 of file tcpip.h.

__tcpip_protocol

struct tcpip_protocol udp_protocol __tcpip_protocol   __table_entry ( TCPIP_PROTOCOLS, 01 )

Declare a TCP/IP transport-layer protocol.

Definition at line 182 of file tcpip.h.

TCPIP_NET_PROTOCOLS

#define TCPIP_NET_PROTOCOLS   __table ( struct tcpip_net_protocol, "tcpip_net_protocols" )

TCP/IP network-layer protocol table.

Definition at line 185 of file tcpip.h.

__tcpip_net_protocol

#define __tcpip_net_protocol   __table_entry ( TCPIP_NET_PROTOCOLS, 01 )

Declare a TCP/IP network-layer protocol.

Definition at line 189 of file tcpip.h.

Enumeration Type Documentation

tcpip_st_flags

enum tcpip_st_flags

TCP/IP address flags.

Enumerator
TCPIP_BIND_PRIVILEGED	Bind to a privileged port (less than 1024) This value is chosen as 1024 to optimise the calculations in tcpip_bind().

Definition at line 61 of file tcpip.h.

                    {
        /** Bind to a privileged port (less than 1024)
         *
         * This value is chosen as 1024 to optimise the calculations
         * in tcpip_bind().
         */
        TCPIP_BIND_PRIVILEGED = 0x0400,
};

Function Documentation

FILE_LICENCE()

FILE_LICENCE

(

GPL2_OR_LATER_OR_UBDL

)

FILE_SECBOOT()

FILE_SECBOOT

(

PERMITTED

)

generic_tcpip_continue_chksum()

uint16_t generic_tcpip_continue_chksum	(	uint16_t	partial,
		const void *	data,
		size_t	len
	)

Calculate continued TCP/IP checkum.

Parameters

partial	Checksum of already-summed data, in network byte order
data	Data buffer
len	Length of data buffer

Return values

cksum

Updated checksum, in network byte order

Calculates a TCP/IP-style 16-bit checksum over the data block. The checksum is returned in network byte order.

This function may be used to add new data to an existing checksum. The function assumes that both the old data and the new data start on even byte offsets; if this is not the case then you will need to byte-swap either the input partial checksum, the output checksum, or both. Deciding which to swap is left as an exercise for the interested reader.

Definition at line 171 of file tcpip.c.

                                                                        {
        unsigned int cksum = ( ( ~partial ) & 0xffff );
        unsigned int value;
        unsigned int i;
        
        for ( i = 0 ; i < len ; i++ ) {
                value = * ( ( uint8_t * ) data + i );
                if ( i & 1 ) {
                        /* Odd bytes: swap on little-endian systems */
                        value = be16_to_cpu ( value );
                } else {
                        /* Even bytes: swap on big-endian systems */
                        value = le16_to_cpu ( value );
                }
                cksum += value;
                if ( cksum > 0xffff )
                        cksum -= 0xffff;
        }
        
        return ( ~cksum );
}

References be16_to_cpu, data, le16_to_cpu, len, and value.

Referenced by tcpip_okx(), and tcpip_random_okx().

tcpip_rx()

int tcpip_rx	(	struct io_buffer *	iobuf,
		struct net_device *	netdev,
		uint8_t	tcpip_proto,
		struct sockaddr_tcpip *	st_src,
		struct sockaddr_tcpip *	st_dest,
		uint16_t	pshdr_csum,
		struct ip_statistics *	stats
	)

Process a received TCP/IP packet.

Parameters

iobuf	I/O buffer
netdev	Network device
tcpip_proto	Transport-layer protocol number
st_src	Partially-filled source address
st_dest	Partially-filled destination address
pshdr_csum	Pseudo-header checksum
stats	IP statistics

Return values

rc	Return status code

This function expects a transport-layer segment from the network layer. The network layer should fill in as much as it can of the source and destination addresses (i.e. it should fill in the address family and the network-layer addresses, but leave the ports and the rest of the structures as zero).

Definition at line 41 of file tcpip.c.

                                             {
        struct tcpip_protocol *tcpip;

        /* Hand off packet to the appropriate transport-layer protocol */
        for_each_table_entry ( tcpip, TCPIP_PROTOCOLS ) {
                if ( tcpip->tcpip_proto == tcpip_proto ) {
                        DBG ( "TCP/IP received %s packet\n", tcpip->name );
                        stats->in_delivers++;
                        return tcpip->rx ( iobuf, netdev, st_src, st_dest,
                                           pshdr_csum );
                }
        }

        DBG ( "Unrecognised TCP/IP protocol %d\n", tcpip_proto );
        stats->in_unknown_protos++;
        free_iob ( iobuf );
        return -EPROTONOSUPPORT;
}

References DBG, EPROTONOSUPPORT, for_each_table_entry, free_iob(), ip_statistics::in_delivers, ip_statistics::in_unknown_protos, tcpip_protocol::name, netdev, tcpip_protocol::rx, tcpip_protocol::tcpip_proto, and TCPIP_PROTOCOLS.

Referenced by ipv4_rx(), and ipv6_rx().

tcpip_tx()

int tcpip_tx	(	struct io_buffer *	iobuf,
		struct tcpip_protocol *	tcpip_protocol,
		struct sockaddr_tcpip *	st_src,
		struct sockaddr_tcpip *	st_dest,
		struct net_device *	netdev,
		uint16_t *	trans_csum
	)

Transmit a TCP/IP packet.

Parameters

iobuf	I/O buffer
tcpip_protocol	Transport-layer protocol
st_src	Source address, or NULL to use route default
st_dest	Destination address
netdev	Network device to use if no route found, or NULL
trans_csum	Transport-layer checksum to complete, or NULL

Return values

rc	Return status code

Definition at line 92 of file tcpip.c.

                                                                 {
        struct tcpip_net_protocol *tcpip_net;

        /* Hand off packet to the appropriate network-layer protocol */
        tcpip_net = tcpip_net_protocol ( st_dest->st_family );
        if ( tcpip_net ) {
                DBG ( "TCP/IP sending %s packet\n", tcpip_net->name );
                return tcpip_net->tx ( iobuf, tcpip_protocol, st_src, st_dest,
                                       netdev, trans_csum );
        }

        free_iob ( iobuf );
        return -EAFNOSUPPORT;
}

References DBG, EAFNOSUPPORT, free_iob(), tcpip_net_protocol::name, netdev, sockaddr_tcpip::st_family, tcpip_net_protocol(), and tcpip_net_protocol::tx.

Referenced by icmp_tx_echo(), ndp_tx_ll_addr(), tcp_xmit_reset(), tcp_xmit_sack(), and udp_tx().

tcpip_net_protocol()

struct tcpip_net_protocol* tcpip_net_protocol

(

sa_family_t

sa_family

)

Find TCP/IP network-layer protocol.

Parameters

sa_family

Address family

Return values

tcpip_net

TCP/IP network-layer protocol, or NULL if not found

Definition at line 69 of file tcpip.c.

                                                                         {
        struct tcpip_net_protocol *tcpip_net;

        for_each_table_entry ( tcpip_net, TCPIP_NET_PROTOCOLS ) {
                if ( tcpip_net->sa_family == sa_family )
                        return tcpip_net;
        }

        DBG ( "Unrecognised TCP/IP address family %d\n", sa_family );
        return NULL;
}

References DBG, for_each_table_entry, NULL, tcpip_net_protocol::sa_family, and TCPIP_NET_PROTOCOLS.

Referenced by efi_pxe_install(), efi_pxe_start(), efi_pxe_udp_deliver(), tcpip_mtu(), tcpip_netdev(), and tcpip_tx().

tcpip_netdev()

struct net_device* tcpip_netdev

(

struct sockaddr_tcpip *

st_dest

)

Determine transmitting network device.

Parameters

st_dest

Destination address

Return values

netdev

Network device, or NULL

Definition at line 115 of file tcpip.c.

                                                                    {
        struct tcpip_net_protocol *tcpip_net;

        /* Hand off to the appropriate network-layer protocol */
        tcpip_net = tcpip_net_protocol ( st_dest->st_family );
        if ( tcpip_net )
                return tcpip_net->netdev ( st_dest );

        return NULL;
}

References tcpip_net_protocol::netdev, NULL, sockaddr_tcpip::st_family, and tcpip_net_protocol().

Referenced by efi_iscsi_path(), ibft_fill_target_nic_association(), and ibft_netdev_is_required().

tcpip_mtu()

size_t tcpip_mtu

(

struct sockaddr_tcpip *

st_dest

)

Determine maximum transmission unit.

Parameters

st_dest

Destination address

Return values

mtu	Maximum transmission unit

Definition at line 132 of file tcpip.c.

                                                    {
        struct tcpip_net_protocol *tcpip_net;
        struct net_device *netdev;
        size_t mtu;

        /* Find appropriate network-layer protocol */
        tcpip_net = tcpip_net_protocol ( st_dest->st_family );
        if ( ! tcpip_net )
                return 0;

        /* Find transmitting network device */
        netdev = tcpip_net->netdev ( st_dest );
        if ( ! netdev )
                return 0;

        /* Calculate MTU */
        mtu = ( netdev->mtu - tcpip_net->header_len );

        return mtu;
}

References tcpip_net_protocol::header_len, mtu, net_device::mtu, netdev, tcpip_net_protocol::netdev, sockaddr_tcpip::st_family, and tcpip_net_protocol().

Referenced by tcp_open().

tcpip_chksum()

uint16_t tcpip_chksum	(	const void *	data,
		size_t	len
	)

Calculate TCP/IP checkum.

Parameters

data	Data buffer
len	Length of data buffer

Return values

cksum

Checksum, in network byte order

Calculates a TCP/IP-style 16-bit checksum over the data block. The checksum is returned in network byte order.

Definition at line 204 of file tcpip.c.

                                                       {
        return tcpip_continue_chksum ( TCPIP_EMPTY_CSUM, data, len );
}

References data, len, tcpip_continue_chksum(), and TCPIP_EMPTY_CSUM.

Referenced by gdbudp_send(), icmp_tx_echo(), icmpv4_rx(), ipv4_rx(), ipv4_tx(), ndp_tx_ll_addr(), tcp_xmit_reset(), tcp_xmit_sack(), and udp_tx().

tcpip_bind()

int tcpip_bind	(	struct sockaddr_tcpip *	st_local,
		int(*)(int port)	available
	)

Bind to local TCP/IP port.

Parameters

st_local	Local TCP/IP socket address, or NULL
available	Function to check port availability

Return values

port	Local port number, or negative error

Definition at line 215 of file tcpip.c.

                                                    {
        uint16_t flags = 0;
        uint16_t try_port = 0;
        uint16_t min_port;
        uint16_t max_port;
        unsigned int offset;
        unsigned int i;

        /* Extract parameters from local socket address */
        if ( st_local ) {
                flags = st_local->st_flags;
                try_port = ntohs ( st_local->st_port );
        }

        /* If an explicit port is specified, check its availability */
        if ( try_port )
                return available ( try_port );

        /* Otherwise, find an available port in the range [1,1023] or
         * [1025,65535] as appropriate.
         */
        min_port = ( ( ( ~flags ) & TCPIP_BIND_PRIVILEGED ) + 1 );
        max_port = ( ( flags & TCPIP_BIND_PRIVILEGED ) - 1 );
        offset = random();
        for ( i = 0 ; i <= max_port ; i++ ) {
                try_port = ( ( i + offset ) & max_port );
                if ( try_port < min_port )
                        continue;
                if ( available ( try_port ) < 0 )
                        continue;
                return try_port;
        }
        return -EADDRINUSE;
}

References EADDRINUSE, flags, ntohs, offset, random(), sockaddr_tcpip::st_flags, sockaddr_tcpip::st_port, and TCPIP_BIND_PRIVILEGED.

Referenced by ping_open(), tcp_open(), and udp_open_common().